反应详情

2-Bromo-5-fluoro-benzotrifluoride (XVII) (50 g, purchased from ABCR, F01421) is dissolved in 750 mL of dichloromethane. Potassium-nitrate (60.54 g) is added under stirring, followed by slow addition of sulfuric acid (587.3 g, 20% SO3, Riedel de Haen 30736). The temperature of the reaction mixture is kept at 25-30° C. by gentle cooling during the addition of the sulfuric acid. The reaction mixture is stirred for additional 25 hours at room temperature, after which time an IPC indicated >97% conversion. For work-up, the layers are separated and the acid layer is extracted by stirring with dichloromethane (2×300 mL). The dichloromethane phases are combined and washed sequentially with 1,000 mL of saturated aqueous NaHCO3 solution, 1,000 mL of aqueous sulfamic acid solution (5% m/m), 1,000 mL of saturated aqueous NaHCO3 solution and 1,000 mL of water. The dichloromethane solution is dried on anhydrous MgSO4 and the solvent is evaporated under reduced pressure to obtain 2-bromo-5-fluoro-1-nitro-3-trifluoromethyl-benzene (XVIII) as a yellow liquid. GC-MS: m/z: 287, 268, 257, 241, 229. These mass peaks are accompanied by the corresponding isotope peaks characteristic for bromine containing compounds. IR (film): 3101, 1618, 1591, 1554, 1454, 1423, 1365, 1319, 1232, 1186, 1153, 1113, 883 cm−1.

1. customis kept at 25-30° C.
2. stirringThe reaction mixture is stirred for additional 25 hours at room temperature
3. customFor work-up, the layers are separated
4. extractionthe acid layer is extracted
5. stirringby stirring with dichloromethane (2×300 mL)
6. washwashed sequentially with 1,000 mL of saturated aqueous NaHCO3 solution, 1,000 mL of aqueous sulfamic acid solution (5% m/m), 1,000 mL of saturated aqueous NaHCO3 solution and 1,000 mL of water
7. dry with materialThe dichloromethane solution is dried on anhydrous MgSO4
8. customthe solvent is evaporated under reduced pressure